Contra: Shattered Soldier (PS2) | The first level
This side-scrolling, 2D shooter is famed for two things: being ungodly difficult, and reviving a classic code that gave you a zillion more lives but that still didn't help much because the game remained so damn... bloody... DIFFICULT.
However, the good news is that the first level is all you need to sweat through to experience the best this game has to offer. By rendering everything in 3D and making the explosions retina-searingly bright, the developers somehow created a game that was visually arresting despite the fact that 90% of it was brown or gray. Toasting mammoth mosquito-lizards with a flamethrower is still impressive today, blasting away at jet-pack-mounted chumps and burrowing mechasnakes while skiing down a mountain is just crazy enough to rock, and the boss entrance is the whole reason this level made our list.
Crackdown (Xbox 360) | Agency Tower
This superhero sandbox game was never about missions, levels, bosses... or structure whatsoever, really. The best parts come when you're simply running, jumping and climbing around the city like Spider-Man on steroids. Reaching the top of the iconic tower at Crackdown's center is the ultimate test of your freakish powers... and the Achievement you receive for diving off afterwards is the ultimate reward.
Defender (arcade) | Any level in which you lose your last human
Defender is an old time classic, with a crazy control panel and relentless difficulty that made it one of the most legendary arcade games of all time. The sky is literally choked with several threats to your life per second. There are landers stealing your humans and turning them into hyper-aggressive mutants. There are bombers which lay mines and pods that burst into swarms of smaller enemies. And if you try to dawdle and make sense of it all, crazy-fast baiters are spawned specifically to hurry you up.
Then, just when you think things can't get any more manic, your last remaining human is kidnapped by a lander and turned into a mutant. The result? The whole world explodes and the number of enemies eager to shove hot laser up your space ass roughly quintriples.
At that moment, your life expectantly can typically be measured in seconds and counted off on your fingers. Most arcade games at least let you think you had a shot at winning, but when the aliens actually brought in more help after they'd blown up the planet, Defender's message became desolately clear. It was, simply: "I am coming to kill you. RIGHT NOW."